i have a preditor tank and for some reason they love to eat next to the overflow, so needless to say they dirtyness of the preidtors goes straight to the filter and skimmer. if i dont clean it when it needs ( i usually check it every day). but a few times i have forgotten and it over flowed back into the tank. when this happens it makes the water look green and alge grows faster, imo its like putting a concentrated dose slime and smellyness into the tank. other than making my weekly maintenance smellier and harder. i havent seen any "destruction" from it. although you dont want that that stuff hitting your tank for a long period of time it shouldnt be a problem for a short period.
also what is the consistancy of your skimmate? soupy watery or sludge...lol....